biology unit 5 - body systems

endocrine system

insulin - beta cell of pancreas - decrease blood glucose

glucagon - alpha cell of pancreas - ^ blood glucose

blood glucose regulation

1. low blood glucose - a-cell secrete glucagon into bloodstream - reach liver. Blood glucose ^ - glycogen hydrolysed into glucose

2. high blood glucose - bcell secrete insulin into blood - reach liver. Blood glucose lowers - liver stores excess glucose as glycogen 

control of blood glucose level - consequence if they arent maintained

a. homeostasis is the maintenance of a constant internal environment

b. the pancreas produces hormones that control the levels of glucose

c. if glucose levels in blood are high, beta-cells of pancreas produce insulin

e. liver stores excess glucose as glycogen

f. if glucose levels in blood are low, alpha-cells of the pancreas produce glucagon

g. Glucagon causes the liver to break down glycogen into glucose, increase levels of glucose in the blood

i. negative feedback controls the glucose levels

consequences:

j. if the pancreas produces little/no insulin a person can develop type I diabetes

k. dependent on injections of insulin

l. type II diabetes occurs when the body becomes resistant to insulin

m. type II diabetes can be controlled by diet and exercise ✔

temperature change detected by

thermoreceptors

thermoregulation

heat &cold

Detected by hypothalamus Thyroid gland secretes less thyroxin Effects: 1. Vasodilation Blood arterioles dilate, more blood pass near skin surface to radiate off heat 2. Sweating - sweat droplets will absorb body heat to evaporate 3. Hair erectile muscles relax, hair lies flat  4. Reduced metabolic rate 5. Reduced cell respiration in brown adipose tissue (BAT)

Detected by hypothalamus Thyroid gland secretes more thyroxin Effects: 1. Vasoconstriction Blood arterioles constrict, blood pass beneath the fat layer to insulate heat 2. Shivering - this causes muscle contraction; cells respire more to produce heat. 3. Hair erectile muscles contract, hair stays upright 4. Increased metabolic rate 5.  Increased cell respiration in brownadipose tissue (BAT)

brown adipose tissue 

• Cellular respiration normally produces heat as a byproduct. 

• Mitochondria in brown adipose tissue are able to uncouple cellular respiration from ATP synthesis. 

• Glucose can be broken down only for heat generation. 

kidney function

1. excretion : removal of body waste from metabolic pathways

2. osmoregulation : control of water balance of blood , tissue/cytoplasm

nephron structure

• glomerulus - site of ultrafilatration - molecules filtered based on size

• afferent, efferent arteriole ( afferent wider → increase pressure)

• bowsman capsule - ultrafiltration

• proximal convoluted tubule - selective reabsorption

• loop of henle- establish a salt gradient in mendulla

• diastle tubule -final site for reabsorption of water&salt

• collecting duct - site of osmoregulation

nephon role in kidney

1. ultrafiltration

2. reabsorption

3. excretion 

ultrafiltration 

Separating substances based on size with the help of blood pressure.

• Plasma escapes from blood capillaries in glomerulus into the Bowman’s capsule due to:

1) Very high blood pressure : efferent arterioles are narrower than the afferent arterioles

2) Large pores in the capillary walls

• allow any molecules to pass through but there are two filters beyond the pores that only small to medium sized particles can pass through.

  • Basement membrane – a gel on the outside of the capillary, with small gaps through a mesh of protein fibres

  • Filtration slits – narrow gaps between the foot, possess of podocyte cells where they wrap around the capillaries

filtrate contains all substances in blood plasma except plasma proteins

selective reabsorption

in proximal convoluted tubules (PCT)

• glucose,amino acid, hormones, mineral , water - reabsorpted here 

• PCT: microvili cell lining - ^ SA for reabsorption of filtrate 

• mitochondria : reabsorption is active transport 

• reabsorbed in tubule cell - passive diffusion down the bloodstream

• some minerals and vitamin active transport via protein pump/carrier protein

• glucose active transported across membrane in symport of sodium 

• water - osmosis 

establish salt concentration in loop of henle

loop of henle

• ascending limb: impermeable to water, permeable to salt

• desending limb: permeable to water, impermeable to salt

1. upper region: pumps out Na+ active transport - ^ ion concentration outside. → ^ solute potential, decrease water potential outside

2. water move out of descending limb by osmosis 

3. movement of water → makes fluid in descending limbmore concentrated as it move down to bottom region → increase concentration of Na and Cl , results in even more Na+ moving out of bottom of ascending limb

4. salt concentration greater in bottom region

→maintains a hypertonic environment

osmoregulation - ADH ( dehydration)

hypertonic medulla- draws water from osmosis

ADH hormone released by posterior pituitary gland in response to dehydration

ADH ^ permeability of collecting duct to water , allowing more water reabsorbed by osmosis via aquaporin 

less water remain in filtrate - urine more concentrated

individual is rehydrated, ADH level decrease, less water absorb in collecting duct 

emergent property- cheetah

flexible spine : spring during running - increase stride length

longer hind limb : enable longer stride

cerebrum

biggest part in the brain , two halves - cerebrum hemispheres

→ advance mental activity

consist of of 5 idiffernet part

• corpus callosum ( band connect two cerebrum hemisphere)

• frontal(learning) , temporal( auditory) , parietal (sensory) and occuptal (visual) lobes

spinal cord responsible for

• unconscious processing

input of CNS

input

• Changes in the external or internal environment → detected by receptors, sensory neuron convey signal → CNS

swallowing of good, Egestion - CNS

role of cerebellum

• receive information from cerebrum, spinal cord, brainstem 

• cerebrum motor cortex receive movement

• movement begins, cerebellum receive feedback impluses from various area of body - sent out impluse to coordinate movement and time 

• walking, hand movement…

hypothamus and pituitary gland 

hypothamuls maintain homeostasis -. lining endocrine system to nervous system

respond to signal by inhibit/stimulate pituitary gland 

nuclei in hypothalamus - control release of hormones in pituitary gland

melatonin

circadian rhythm ( 24hr of physical, behavioural and mental) → set by SCN cells in hypothalamus → controls secretion of serotonin in pineal glands 

• light inhibit secretion, night secretion ^ , decreases by age 

→adjusted by exposure of light 

cell in retina detect light - send neural impluse to SCN - adjust timing of release of metatonin 

epinephrine

• flight or fight response

• Prepare body for vigorous, immediate response with intense muscle contractions.

• secreted by adrenal glands 

peristalsis control

wavelike contractions of smooth muscle → peristalsis

Swallowing and egestion are voluntary actions controlled under the CNS.

Peristalsis is an involuntary action controlled by the (ENS)

• ensure material through gut is coordinated 

• stretch receptors in gut - detect position + direction of movement of bolus 

• various excitatory& inhibitory neurotransmitter - released on longitudinal+circular muscle around bolus - coordinate contraction

trophic

the turning of all or part of an organism in a particular direction in response to an external stimulus.

ex. shoot grows towards light - positive phototrophism

root bend away from light - negative phototropism

Phytochromes

plant hormones that regulate physiological processes in plants.

phytochromes example

 auxin

• growth hormone

• produced in shoot apical meristem

• cell elongation for tropic movements + inhibit growth of lateral buds- vertical elongation

cytokinins

• promote cell division

• abundant in growing tissue 

• produced in root , pass to leaves and fruits 

• promote cell division, differentiation of meristem

auxin

• produced in tip of stem, promote cell elongation

• tropic movement in plants - auxin uneven distribution

• move away from light stimulus

sun on top 

• diffuse evenly - all cell grow at same rate

• shoot grow vertically upwards

sun on side

• auxin molecules move towards shaded side of shoot , away from light

• ^ concentration on auxin - rapid cell elongation + growth on that side

• uneven growth , cause stem bend towards light source

phototrophism

the turning of plant in one direction in response to external stimuli

phototrophism in auxin - auxin gradient

• Auxin is produced at the apex (tips) of the shoot.

• When light in the shoot is detected → trigger movements of auxins by active transport by auxin efflux pumps

• Efflux pump pumps auxin from cytoplasm→ cell wall, diffused to the next cell.

• enters the cell→ auxin is trapped inside the cytoplasm until the efflux pump pumps it out again.

• Auxin efflux pumps→ move in response to differences in light intensity→ creating a concentration gradient of auxin from lower on the lighted side and higher in the shaded side.

phototrophism in auxin - elongation of cell 

• Plant cells contain auxin receptor. Auxin binds→ transcription of the genes for proton pump 

• Expression of these genes → the secretion of hydrogen ions into the cell wall.

• hydrogen bonds between cellulose , weakened, loosens the cell wall.

• expansion of cell due the increase water uptake and higher turgor pressure.

auxin and cytokinin work together

• Auxin is produced in the shoot and cytokinin is produced in the root.

• Both areas are growing regions of the plant.

• Auxin is responsible for cell elongation, cytokinin is responsible for cell division.

• Both phytochromes needs to be transported to the opposing growth regions → regulate the growth of all parts of the plant and integrate both signals.

Cytokinin is transported through xylem up the plant and auxin is transported through phloem down the plant.

• Together, the phytohormones work on meristems to integrate cell growth

• The ratio of the two determines whether it results in:

  • Synergism - work together to stimulate a process 

  • Antagonism - have opposing effects to regulate a process 

fruit ripening - feedback control

• Positive feedback: the amplification of response to a stimulus

• Ethylene (Ethene) is produced in ripping fruits.

• Once the ripening process starts, fruit produces more ethene.

• one fruit started to produce ethen → cause surrounding fruit to ripen and produce even more ethene.

This helps fruits to become more attractive to herbivores→ increasing the seed dispersal rate

skeleton (2)

• exoskeleton ( chitin )

• endoskeleton ( bones)

joint (2)

• hinge joint ( elbow and knee)

  • one plant of movement

  • bend & straight

• ball and socket joint ( hips, shoulder)

  • large range of movement

  • protraction, retraction , abduction, adduction , rotation

measure joint

goniometer

most allowing movement joint

synovial joint - human hip joint 

 

Bone (Femur & Pelvis)

Cartilage

Synovial fluid

Ligaments

Muscles

Tendons

function

bone- anchorage for muscle & ligants, guide movement 

muscle - provide force for movemet 

cartilage - smooth connective tissuet that covers the end of bone to reduce friction 

synovial fluid - lubricate joint reduce friction

ligaments - slight elastic tissue - attaches bones to bones 

tendons - non elastic tissue - attaches muscle to bone

skeletal muscle

• attacth bones - cause movement of animal body 

• It consists of large multinucleated cells called muscle fibers.

• There are also mitochondria between the myofibrils.

level of organisation 

muscle fibres → myofibris → microfillaments → sacromere 

wra around myofibrils

sacroplamatic reticulum

skeletal muscle & electrical impluse

Skeletal muscles are voluntary muscles that requires electrical impulse from the brain.

• Electrical impulse sent from brain through motor neuron → neuromuscular junction.

Each motor neuron has a set number of muscle fibers that it control called a motor unit.

motor unit + function

• contraction of skeletal muscle 

• include single motor neuron & muscle fibres

• muscle fibre contract when stimulated by motor neuron

• stimulus pass through neuron , through synapse- neuromuscular junction to muscle fibre

• require neurotransmitter : acetylcholine ( basically just the normal neurotransmitter process) 

sacromere

• two protein filaments

• subunit of myofibrils 

• between two Z-lines

• myosin 

  • thick , dark bands 

  • head that forms cross bridge by binding to actin 

• actin 

  • thin, light bands 

  • lengthening and shortening of sarcomere

  • attach at the end of Z lines

crose bridge cycle

1. When a nerve impulse arrives at the neuromuscular junction,calcium ions are released from the sarcoplasmic reticulum

2. calcium bind with troponin, change shape, move tropomyosin to expose the myosin-binding site on actin

3. Myosin heads bind to actin, forming crossbridges 

4. Myosin releases ADP and P_i, causing the power stroke - pulls the actin filament towards the centre of the sarcomere

5. ATP binds to myosin, breaking the crossbridges

6. ATP is hydrolysed to ADP and P_i, provide energy that “cock” the myosin head away from the center

7. Myosin heads bind to actin at a new binding site further along the sarcomere

The cycle continues until Calcium is pumped back into the sarcoplasmic reticulum, or there is no ATP available

titin

contraction of antagonistic muscle → creates energy →  needed to lengthen a muscle, which stretches titin. titin recoils → release energy → adds to the force of contraction in that muscle (provide supplemental force)

• prevent overstretching of sacromere 

• holds myosin filaments in place 

Explain how a skeletal muscle contracts

neuron

1. cell body - cytoplasm&nucleus , elongated nerve fibre- conduct electrical impluse

2. dendrities - shorter fibres, projecting from cell body

3. nucleus

4. schwann cell

5. node of ranvier

6. axon terminal

sodium potassium pump

na+ binds - stimulate phosphorylation by ATP- protein change shape , release NA+

k+ binds, trigger release of phosphate group - protein returns original shape - k+ out, NA+ site receptive

oscilloscope trace (3)

1. resting potential  - 70mV- neuron not stimuated

na+ pump out, K+ diffuse in 

2. action potential +40mV

stimulus reaches threshold, activate neuron 

na+ k+ pump turn off, sodium ion channel opens → influx of sodium → +40

3. refractory period - more negative than -70 

Na+K+ pump on 

potassium ion channel opens- k+ diffuse out - axon membrane impermeable to potassium, none diffuse in 

• more negative than 70

X new electrical impluse can pass through befoe neuron return to resting potential 

ensure electrical impluse pass through 1 direction

depolarization & repolarization

During depolarization Na⁺ diffuses into the cell

• making the membrane potential positive

During repolarization K⁺ diffuses out of the cell

• restoring a negative membrane potential

saltatory conduction

• schwann cell wrap axon with myelin sheath containing fatty substance

• insulate electrical impluse 

• as only node of ranvier is site of depolarization - electrical impluse jump from node to node 

• speeds up the electrical conduction 

speed of impluse factors affecting it

temperature - hotter, quicker

axon diameter - larger, faster

schwann cell

synapse - neurotransmitter

1. electrical impluse arrive at the end of postsynaptic neuron. calcium ion channel opens - influx of calcium 

1. vesivle containing neurotransmitter migrates to presynaptic knob 

2. neurotransmitter release synapse via exocytosis

3. diffuses down the synaptic cleft 

4. releases & binds to postsynaptic receptor 

5. sodium channel opens - generate electrical impluse in postsynaptic neuron 

excitatory and inhibitory channels

excitatory:

• neuroreceptors that are sodium (Na⁺) channels

• channels open, positive ions diffuse in, causing a depolarization

• excitatory postsynaptic potential (EPSP) -stimulate an action potential

acetylcholine, glutamate.

inhibitory 

• neurotransmitter that are chloride(Cl-) chanels

• channel open - negative ion diffuse in - hyperpolarization 

• inhibitory postsynaptic potential - supress action potential 

• impluse in one neuron inhibit the impluse in the next

GABA

acetylcholine - neurotransmitter 

exist in many synapse - inculding neuromusular junctions 

• break down ACh in synaptic cleft

• Ch ( choline) - absorb in presynaptic neuron - regenerate ACh

propagation of nerve impulses

• action potential of one part triggers action potential in another part

• Na+ diffuse from a region with action potential to next region in resting potential

• diffusion of NA+ - causes local current - change voltage from resting (-70) to threshold ( -50)  - voltage gated sodium channel opens - causes action potential

exogenous chemical 

• chemical substance that alter the physiological state of organism

block synaptic transmission:neonicotinoids

promote synaptic transmission:cocaine ( excitatory)

drugs affect body in 3 ways 

1. Mimic the neurotransmitter - acts as competitive inhibitor

2. Prevent the breakdown /  re-uptake of neurotransmitter, constantly activate the receptor

3. Prevent the release of neurotransmitter

how neonicotinoids kill honey bees

normal

• AChE break donw ACH - prevent overstimulation & blockage of acetylcholine receptor 

wiht neonicotinoids

• bind to acetylcholine receptor- AChE , cannot break down neonicotinoids → lead to paralysis ( blockage of acetylcholine receptor)

• Neonicotinoid pesticides bind to aceylcholine receptors at post-synaptic membrane of cholinergic synapse of insects

• Cholinesterase does not break down pesticides - remain bound to receptor - prevent acetylcholine from binding

• block synapse transmission - kill honey bees

how cocaine works 

• bind to dopamine reuptake receptor - inhibit reuptake of dopamine 

• dopamine accumulation in synaptic cleft 

• ^ likelihood of parkinson disease, dopamine receptor loses sensitivity to dopamine ( also why cocaine users increase dosage) 

inhibitory neurotransmitter - GABA 

1. gaba bind on ligand gated Cl- channels 

2. makes postsynaptic membrane negative - hyperpolarization 

3. harder for postsynaptic neuron to reach threshold , inhibiting nerve impulse 

ligand function + process

binds to protein receptor, causes a change in metabolism within the cell

• sending cell release signal molecules-ligand → transport to target cell → binds on ligand binding site on receptor → stimulates response in target cell

whole process of chemical signalling is called

single transduction pathways

quorum sensing

• bacteria regulate behaviour based on population density

• coordinate communications between bacteria

• autoinducter(ligand) - concentration reaches a threshold - gene expression of bacteria will be altered

bioluminscent 

V. fisheri bacteria - only bioluminescent in large enough numbers

• mutualistic/symbiotic relationship with Bobtail squid 

• luminscent its underside- camoflage to matches mooonlight - hidefrom predators+sneak up on prey

• V.fischeri in return for homw and nutrient 

quorum sensing in V.Fischeri

v. fischeri releases signal molecules called autoinducer in a low rate

autoinducer passes to external environment , ^ number of bacteria ^ autoinducer concentration 

reaches a threshold - move back into bacteria cell - bind to LuxR receptors 

activated LuxR - bind to DNA binding site : Lux Box

Binding activated genes responsible for production of luciferase ( luminescent protein)

ligand - Hormone & neurotransmitter

hormone

• endocrine system glands release hormone into bloodstream to elicit response w target cell 

• long lasting & widespread - slow (LH from brain to ovary) 

• ex. amine(epinephrine) , protein(FSH) , steriods (progesterone)

neurotransmitter

• nervous system transmit signals through synapse 

• short lived & local effect - fast 

• ex. amino acid (GABA - inhibitory, glutamate - excitatory) , acetylcholine

ligand - cytokinesis & calcium ions

cytokinesis - immune system

calcium ion - secondary messanger in muscle + nervous system 

difference between transmembranbe & intracellular receptors

transmembrane( embedded in cell membrane )

• signals affect permeability 

• bind to receptor - activate transporter ( substance can enter and leave the cell)

• calcium gated ion channel - insulin increase uptake of glucose 

• signals release secondary messenger

• bind to receptor - activate enzyme (affect various aspects of cell)

• GPCR - adrenaline stimulates glycogen breakdown

intracellular ( within cytoplasm)

• hydrophobic signals go through membrane , diffuse to nucleus - bind to receptor which forms transcriptional factor → activates protein synthesis

• estrogen stimulated growth in uterus 

ligand gated ion channel & acetyloine 

• multi pass protein - thread back and forth across the cell membrane - center is a pore, allows sodium ions to pass through 

• pore opens when acetylcholine binds to receptors 

• influx of sodium ion - new action potential on post synaptic knob / muscle contraction at neuromuscular junction

GPCR

• multi transmembrane protein receptor

• acts indirectly on enzyme/ion channel with G-protein 

• ligand binds to extracellular receptor- activated receptor → allow g-rpotein to bind to nucleotide GTP 

• binding of GTP - activate g protein : carry signal into cell , activate other protein and carry out response 

• removal : hydrolysis of GTP - GDP , G- protein can be deactivated and reuse 

GPCR and secondary messager ( & advantages) 

• use seconary messager to produce and amplify a response - cAMP

• cAMP produced when enzyme adenylyl cyclase activated by ATP

• continues a cascade of multiple activations of phosphorylation until final effect is reached 

• ex. human liver convery glycogen - glucose in response to adrenaline and glucagon 

advantages -

one hormone - differnet effects in a celldifferent

two hormone - same affect in a cell  

each hormone - different effects - different cells 

epiphrine receptors + break down of glycogen

• g-protein coupled receptors which uses secondary messager of cAMP 

• g-protein activate adenylyl cyclase - convert ATP - cAMP 

• cAMP activates PKA → PKA phosphorylates + activate protein ( enzyme)

• ex. liver - oxidation of glycogen to glucose

what is kinase

enzymes that uses atp to phosphorylate molecules

tyrosine kinase with insulin receptor 

• receptors work/link as a enzyme

• a pair of single pass protein with 3 domains

• 1. extrcellular: receptor for ligand (eg. insulin)

• 2. transmembrane : pass through cell membrane once

• 3. intracellular : acts as kinase- autophoryates after binding with insulin

insulin binds to transmembrane receptor

tyrosine kinase enzyme tail on cytoplasm side - phosphorylates each other

trigger signal transduction → glucose transporters inserted in the plasma membrane

glucose uptake into cells 

intracellular receptor on gene expression + examples( function of examples) ( steriod hormones)

steriod hormones - hydrophobuc - pass through cell membrane

bind to receptors inside cell - hormone-receptor complex - diffuse into nucleus - directyl affect gene transcription

ex. progesterone, oestradiol 

progresterone: thickens, maintain endometrium - implantation 

oestradiol : hypothalamous, ^ transcripton of GnRH - increase of LH&FSH. 

positive and negative feedback on signalling pathway

positive

• amplfy cell signalling - enhance response

• end product amplify start point - more product

• blood clot , oestradiol stimulation, labour duirng birth

negative

• dampen cell signalling - inibit response

• end product inhibit start point

• gluvose regulation with insulin+ glucagon 

gas exchange function

1. obtain gases for metabolism

2. release waste products

gas exchange occurs

diffusion - gases travel from high to low concentration to reach diffusion

structure to facilitate gas exchange (4)

1. large SA:V (branches+foldings)

2. permeability of O2 and CO2

3. thin tissue layer minimise diffusion distance

4. moist layer for gases to dissolve 

how is concentration gradient maintained (3) 

1. Dense capillary network around gas exchange surfaces

2. Continuous blood flow

3. Ventilation 

• With air for lungs

• With water for gills

Lungs

trachea

bronchus 

bronchiole 

alveoli

lungs 

ribs 

intercostal muscle 

diaphragm 

definition for ventilation + gas exchange + cellular respiration

1. Ventilation : exchange of air between atmosphere and lungs - breathing

2. Gas exchange : exchange of O2 and CO2 between alveoli and bloodstream - passive diffusion 

3. Cellular Respiration : release of ATP from organic molecules 

exchange on ventilation rate

increase rate exercise > increase cellular respiration > increases uptake of oxygen > increase ATP - breath in faster

By product of cellular respiration increases: Co2 > blood gets acidified > proteins like RBC denatures > dont carry oxygen > dies.

To avoid Co2 accumulation - breath out faster > ventilation rate faster 

respiratory system (5)

1. air travels from nose&mouth - pharynx - trachea

2. air divides into two bronchi

3. right : 2 lobes, left : 3 lobes

4. bronchi - many bronchiole ( increases SA)

5. bronchiole - airsacs: alveoli ( gas exchange w bloodstream occurs)

structure of alveolus

1. thin epithelial layer ( one cell thick ) > minimuze diffusion distances

2. surrounded by rich capillaries layer > increase capacity for ge with blood 

3. spherical in shape > maximize SA for ge 

4. internal surface - covered with surfactant > dissolved gas better able to diffuse in bloodstream + reduce surface tention 

where is pneumocytes

(alveolar cells) - line the alveoli , comprise the majority of inner surface of lungs

what is alveoli made out of 

• type 1 + type 2 pneumocytes 

type 2 pneumocytes 

• secrete alveolar fluid → contain surfactant

how surfactant works 

• both alveoli have equal surface tension

• left one - smaller radius - higher pressure - hard to inflate, more likely to collapse 

• with surfactant: less surface tension, able to have same pressure - wont collapse 

adaptations for lungs(4)

1. surfactant - decrease pressure

2. short diameter of bronchiole - slow air flow increases efficiency 

3. many alveoli attached at the end - increase SA for gas exchange 

4. extensive capillaries around alveoli - short diffusion distance 

ventilation in antagonistic muscle 

Inhalation  

1. external intercostal muscle - contracts → ribcage move out and up

2. diaphagram - contracts → move down and flattens

3. volume increase in thorax

4. decrease of pressure in lungs compare to atmospheric pressure - air flows into the lungs

exhalation

1. internal intercostal muscle - contracts → ribcage move in and down

2. abdominal - contracts → pushes diaphragm into dome shape

3. volume decrease in thorax

4. increase of pressure in lungs compare to atmospheric pressure - air flows out the lungs

measure lung volume

spirometry

spirometry trace

gas exchange in leaf

• stomata 

• guard cells control opening and closing of stomata 

adaptations of leaf 

waxy cuticle 

palisade layer

spongy mesophyill

xylem&pholem

stoma & guard cells

transpiration

• water lost by stomata 

Water vapour is lost via the stomata

• Diffuses down its concentration gradient into the atmosphere → creating negative pressure in the xylem

• Creates tension that further draws water up the xylem from the roots to the leaves.

Transpiration facilitates:

• Temperature regulation

• Absorption of water and minerals from soil

factors affecting transpiraton

• increase transpiration

  • wind: ^water concentration gradient

  • temperature : ^ saturation point of air 

  • light : ^ photosynthesis 

• decrease transpiration 

  • humidity : decrease water concentration gradient

hemoglobin (location, function , structure)

Location: RBC

Function : transport O2 to respiring tissue, transport byproduct Co2 to lungs

Structure : quaternary , conjucated protein - 4 polypetide with heme group

hemoglobin and oxygen

• coorporative binding

• structure changes - affinity for oxygen ^